A conventional control system outputs a grid power to a load via two parallel power lines. In addition, the power lines are also used for signal transmission from the conventional control system to the load (i.e., power line communication). The conventional control system has the following drawbacks:
1. Interference in the signal as attributed to the grid power is relatively high.
2. Power consumption of the conventional control system is relatively large.
3. Compatibility of the conventional control system with the load is relatively poor.
4. Distortion of the signal is relatively serious when the power lines are relatively long.